I thought I’d finally sit down and write a proper update on the car, because the last few months have been less about throwing parts at it and more about enjoying the setup as it came out of winter hibernation and testing consistency and reliability on 99ron pump fuel (93 octane US pump fuel i believe) and look to the future and think about what Ethanol blends I could run which can give the best bang for buck working alongisde the current WMI system which I think is essential as i'm not going to run full E85 or Methanol fuel.
To recap current setup is fairly straightforward on paper: 13B large street port, G35-1050 (1.21), pump fuel with Renegade octane booster, and 60/40 WMI, running around 26–27psi. At that level, the car managed a 5.58s 100–200, and more importantly, it wasn’t a one-off. It would consistently sit in the mid 5s, run after run in summer heat. That consistency is what made me start questioning things because it didn’t feel like the limit of the setup, just the limit of what I was extracting from it. However, it's a great place to be on a streetport and I genuinely do not need more power or acceleration for street or track use. To put this into perspective an AMG GTR Black Series or a GT2 RS Porsche run similar acceleration numbers and both are monster on track especially the Nurburgring. In fairness, really really happy with the current setup and how it performs and I've enjoyed that as I've got back into testing this year.
Over winter, instead of pushing harder, I went the other way. Same boost, same general setup, but in much better conditions around 10°C ambient. On paper, it should’ve been quicker. Cooler, denser air, more power. I went out expecting it to feel stronger and finally dip lower into the 5s.
But it didn’t.
The car just kept returning 5.60, 5.61, 5.62. Again and again. No real world improvement. If anything, it sometimes felt slightly worse and very sketchy. The reason was obvious, Traction or lack thereof. The 265 cup 2s, no matter what I did; the tyres did not switch on and could not put the power down. Traction really struggled in the midrange, especially as the boost comes in hard, you can feel there’s more there, but it’s not useable or controlled. That old saying "power without control is meaningless" or "spinning's not winning" comes to mind. The torque is blowing the tyres off in 3rd gear and i'm being forced to short shift into 4th and its still running consistent 5.6s range which is a testament that at this stage the car isn’t power-limited, it’s traction-limited.
To combat traction issues I moved from a 265 to a 295 rear tyre, which subjectively helped, but it hasn’t solved it. The car still struggles to put the power down, especially in that midrange where everything comes on strong. You can feel it wanting to go faster, but it just can’t translate it cleanly into forward motion.
I'm going to do some tuning and kill off some torque in the midrange to get the tyres to hook, make it more linear, boring stuff!! Also i believe the other issue is perhaps street focused tyres like ps5 or ps4s would work better in the cold as Cup 2s are well out of their comfort zone at 10*C ambient temps.
I’ve also got a Turblown UIM going on tomorrow, which should help with airflow and wmi distribution, especially up top. After that, it’s straight back out testing to see what it actually does in the real world. The question on everyone's mind including my own...how far will a G35 go or is the 5.5 to 5.6s the ceiling of real world performance on this turbo? Hopefully we should find out soon.
At this point, it feels less like chasing a number and more like figuring out how to let the car do what it’s already capable of.
